PHP survived because it takes nearly no programming skills at all and appeared at the jump when the best Perl options (modperl, fastcgi) were hard to install and the other good high level languages had no real web presence; 15 years ago. This is also why nearly everything done with PHP has been plagued by security problems. If you like the style, stick with it. You can absolutely do the same thing in Perl but it would be silly.

• Catalyst is a decade old already. Mojo isn’t going anywhere. Dancer has a big community. Packages like Template::Toolkit and DBIx::Class have dozens and dozens of contributors, like me and a few other monks.
• No. Perl6 is not ready and it is a much more sophisticated language than Perl5 and PHP. It will not reward junior devs but punish them. It will be one–two years after its first real release when solid frameworks will appear. Till then, here be little but dragons.
• Every web framework has sessions out of the box and Mojo in particular is more secure out of the box. PHP on the other hand is trivial to screw up and write insecure code and there are ooooooodles of terrible examples and advice for it out there. It’s basically guaranteed to mess up if you don’t know good practices. Perl is also… but not as badly or automatically. The community has a strong sense of best practices v dangerous practices.
• Everything in Perl is easy to install excepting some XS/Image packages. perlbrew (update, fixed link), App::cpanm, etc.